1. Field of the Invention
In one of its aspects, the present invention relates to an on-line device for predicting at least one fluid flow parameter in a process. In another of its aspects, the present invention relates to an on-line UV dosimeter for predicting bioassay equivalent does for a given microorganism in a UV disinfection process. In yet another of its aspects, the present invention relates to a method for on-line prediction of at least one fluid flow parameter in a process.
2. Description of the Prior Art
Fluid treatment systems are known generally in the art.
For example, U.S. Pat. Nos. 4,482,809, 4,872,980 and 5,006,244 (all in the name of Maarschalkerweerd and all assigned to the assignee of the present invention and hereinafter referred to as the Maarschalkerweerd #1 patents) all describe gravity fed fluid treatment systems which employ ultraviolet (UV) radiation.
Such systems include an array of UV lamp frames which include several UV lamps each of which are mounted within sleeves which extend between and are supported by a pair of legs which are attached to a cross-piece. The so-supported sleeves (containing the UV lamps) are immersed into a fluid to be treated which is then irradiated as required. The amount of radiation to which the fluid is exposed is determined by the proximity of the fluid to the lamps, the output wattage of the lamps and the fluid's flow rate past the lamps. Typically, one or more UV sensors may be employed to monitor the UV output of the lamps and the fluid level is typically controlled, to some extent, downstream of the treatment device by means of level gates or the like.
U.S. Pat. Nos. 5,418,370, 5,539,210 and 5,590,390 (all in the name of Maarschalkerweerd and all assigned to the assignee of the present invention and hereinafter referred to as the Maarschalkerweerd #2 patents) all describe fluid treatment systems which employ UV radiation. More specifically, the Maarschalkerweerd #2 patents teach an ultraviolet radiation treatment system disposed in an open channel comprising a gravity fed flow of fluid. In a preferred embodiment, after treatment, the fluid is then discharged into a stream, creek, river, lake or other body of water—i.e., this embodiment represent application of the system in a municipal wastewater treatment facility.
Conventionally, in the art of UV radiation treatment systems, the radiation dose in a given irradiation zone has been calculated using the equation:DOSE=tave×Iavewherein tave is the average time that a microbe spends in the irradiation zone and Iave is average UV intensity integrated over the volume in the irradiation zone.
Recently, it has been suggested that this relatively simple calculation can, in certain cases, lead to inaccuracies in the dose which is actually delivered to the fluid being treated—see “Hydrodynamic behaviour in open-channel UV systems: Effects on microbial inactivation” (K. Chiu, D. A. Lyn, and E. R. Blatchley III, CSCE/ASCE Environmental Engineering Conference (1997), pages 1189–1199). This can have significant consequences since many UV radiation treatment systems are specified in large part using such a calculation. Further, the calculation presumes that the system is operating in an optimum state at all times and thus, for example, would not take into account a situation where one or more of the UV radiation sources is not operating properly or at all.
Accordingly, there remains a need in the art for a device which would allow one to predict with improved accuracy the dose delivered to the flow of fluid. It would be advantageous if such a device had widespread use beyond that in predicting dose delivered to a flow of fluid in a UV radiation treatment system—i.e., beyond use as a dosimeter.